Add top-level module in route file pattern

Rails 4's route loader does not reliably persist top-level module
definitions across the routes-reload boundary. A pattern like

  module Constraints
    class Admin
      ...
    end
  end

defined inside a config/routes/*.rb file may evaluate at boot but
the Constraints constant does not survive subsequent reloads, and
downstream uses like `constraints Constraints::Admin do ... end`
raise NameError: uninitialized constant Constraints. Rails 3.2
handled this more leniently — modules defined in route files
persisted across reload boundaries.

Fix is two-part, branched on NextRails.next?:

1. Move the module's class definitions to convention paths
   (e.g. config/routes/constraints/admin.rb for Constraints::Admin)
   so Rails autoload finds them.

2. Add the parent directory to config.autoload_paths, also gated by
   NextRails.next?, so the new layout only applies on the Rails 4+
   side. Rails 3.2 still wants the modules at the original path
   inside the route file.

The exclude regex skips RSpec:: and Constraints:: references that
match the leading `module` pattern but are not actual module
definitions.

Classified high_priority / kind: breaking — Rails 4 raises NameError
on the first reload that hits the dropped constant.

Author: JuanVqz

rails-upgrade/detection-scripts/patterns/rails-40-patterns.yml

@@ -192,6 +192,16 @@ upgrade_findings:
       fix: "Replace hyphens with underscores and CamelCase with snake_case in `to:` values. URL paths keep their original form. The snake_case form resolves to the same controller class on Rails 3.2, so the rewrite ships pre-bump and is backwards-compatible. Example: `to: \"my-pages#show\"` → `to: \"my_pages#show\"`; `to: \"MyPages#show\"` → `to: \"my_pages#show\"`"
       variable_name: "ROUTES_CONTROLLER_NAMES"
 
+    - name: "Top-level module defined in a route file (autoload-on-reload boundary)"
+      kind: "breaking"
+      pattern: "^\\s*module\\s+[A-Z]\\w*"
+      exclude: "RSpec::|Constraints::"
+      search_paths:
+        - "config/routes/"
+      explanation: "Rails 4's route loader does not reliably persist top-level module definitions across the routes-reload boundary. A pattern like `module Constraints; class Admin; ...; end; end` defined inside a `config/routes/*.rb` file may evaluate at boot but the `Constraints` constant does not survive subsequent reloads — downstream uses (e.g. `constraints Constraints::Admin do ... end`) raise `NameError: uninitialized constant Constraints`. Rails 3.2 was more lenient — modules defined in route files persisted across reload boundaries"
+      fix: "Two-part fix, gated by `if NextRails.next?`. (1) Move the module's class definitions to convention paths (e.g. `config/routes/constraints/admin.rb` for `Constraints::Admin`) so Rails autoload finds them. (2) Add the parent directory to `config.autoload_paths` in `config/application.rb`: `if NextRails.next?; config.autoload_paths += [Rails.root.join(\"config/routes\")]; end`. Do NOT move the files unconditionally — Rails 3.2 still wants them at the original path inside the route file. Branching the autoload_paths assignment without moving the files means the modules load via Rails convention on the next side and route-file evaluation on the current side"
+      variable_name: "ROUTES_TOP_LEVEL_MODULE_AUTOLOAD"
+
   medium_priority:
     - name: "rescue_action method"
       kind: "breaking"